[fix 1385979] Check if the item is valid first

openlp/core/ui/settingsform.py

@@ -143,6 +143,9 @@ class SettingsForm(QtGui.QDialog, Ui_SettingsDialog, RegistryProperties):
         """
         # Get the item we clicked on
         list_item = self.setting_list_widget.item(item_index)
+        # Quick exit to the left if the item doesn't exist (maybe -1?)
+        if not list_item:
+            return
         # Loop through the list of tabs in the stacked layout
         for tab_index in range(self.stacked_layout.count()):
             # Get the widget

tests/functional/openlp_core_ui/test_settingsform.py

@@ -29,10 +29,10 @@
 """
 Package to test the openlp.core.ui.settingsform package.
 """
+from PyQt4 import QtGui
 from unittest import TestCase
 
 from openlp.core.common import Registry
-from openlp.core.ui.generaltab import GeneralTab
 from openlp.core.ui.settingsform import SettingsForm
 
 from tests.functional import MagicMock, patch
@@ -62,7 +62,7 @@ class TestSettingsForm(TestCase):
                 patch.object(settings_form.setting_list_widget, 'addItem') as mocked_add_item:
             settings_form.insert_tab(general_tab, is_visible=True)
 
-            # THEN: Stuff should happen
+            # THEN: The general tab should have been inserted into the stacked layout and an item inserted into the list
             mocked_add_widget.assert_called_with(general_tab)
             self.assertEqual(1, mocked_add_item.call_count, 'addItem should have been called')
 
@@ -80,6 +80,25 @@ class TestSettingsForm(TestCase):
                 patch.object(settings_form.setting_list_widget, 'addItem') as mocked_add_item:
             settings_form.insert_tab(general_tab, is_visible=False)
 
-            # THEN: Stuff should happen
+            # THEN: The general tab should have been inserted, but no list item should have been inserted into the list
             mocked_add_widget.assert_called_with(general_tab)
             self.assertEqual(0, mocked_add_item.call_count, 'addItem should not have been called')
+
+    def list_item_changed_invalid_item_test(self):
+        """
+        Test that the list_item_changed() slot handles a non-existent item
+        """
+        # GIVEN: A mocked tab inserted into a Settings Form
+        settings_form = SettingsForm(None)
+        general_tab = QtGui.QWidget(None)
+        general_tab.tab_title = 'mock'
+        general_tab.tab_title_visible = 'Mock'
+        general_tab.icon_path = ':/icon/openlp-logo-16x16.png'
+        settings_form.insert_tab(general_tab, is_visible=True)
+
+        with patch.object(settings_form.stacked_layout, 'count') as mocked_count:
+            # WHEN: The list_item_changed() slot is called with an invalid item index
+            settings_form.list_item_changed(100)
+
+            # THEN: The rest of the method should not have been called
+            self.assertEqual(0, mocked_count.call_count, 'The count method of the stacked layout should not be called')